Several long-standing typos and naming confusions in Policy_sh.SH have been fixed,
standardizing on the variable names used in config.sh.

This will change the behavior of Policy.sh if you happen to have been accidentally relying on the Policy.sh incorrect behavior.
We'd appreciate feedback from anyone using Policy.sh to be sure nothing is broken by this change (c1bd23).

defined %Foo:: now always returns true,
even when no symbols have yet been defined in that package.

This is a side effect of removing a special case kludge in the tokeniser,
added for 5.10.0,
to hide side effects of changes to the internal storage of hashes that to drastically reduce their memory usage overhead.

Calling defined on a stash has been deprecated since 5.6.0,
warned on lexicals since 5.6.0,
and has warned for stashes (and other package variables) since 5.12.0.
defined %hash has always exposed an implementation detail - emptying a hash by deleting all entries from it does not make defined %hash false,
hence defined %hash is not valid code to determine whether an arbitrary hash is empty.
Instead,
use the behaviour that an empty %hash always returns false in a scalar context.

A package declaration can now contain a code block, in which case the declaration is in scope only inside that block. So package Foo { ... } is precisely equivalent to { package Foo; ... }. It also works with a version number in the declaration, as in package Foo 1.2 { ... }. See perlfunc (434da3..36f77d, 702646).

Modules that create threads should now create CLONE_PARAMS structures by calling the new function Perl_clone_params_new(), and free them with Perl_clone_params_del(). This will ensure compatibility with any future changes to the internals of the CLONE_PARAMS structure layout, and that it is correctly allocated and initialised.

perl -h used to mark the -w option as recommended; since this option is far less useful than it used to be due to lexical 'use warnings' and since perl -h is primary a list and brief explanation of the command line switches, the recommendation has now been removed (60eaec).

perlebcdic.pod contains a helpful table to use in tr/// to convert between EBCDIC and Latin1/ASCII. Unfortunately, the table was the inverse of the one it describes, though the code that used the table worked correctly for the specific example given.

The table has been changed to its inverse, and the sample code changed to correspond, as this is easier for the person trying to follow the instructions since deriving the old table is somewhat more complicated.

The table has also been changed to hex from octal, as that is more the norm these days, and the recipes in the pod altered to print out leading zeros to make all the values the same length, as the table that they can generate has them (5f26d5).

perlunicode.pod now contains an explanation of how to override, mangle and otherwise tweak the way perl handles upper, lower and other case conversions on unicode data, and how to provide scoped changes to alter one's own code's behaviour without stomping on anybody else (71648f).

$# and $* were both disabled as of perl5 version 10; this release adds documentation to that effect, a description of the results of continuing to try and use them, and a note explaining that $# can also function as a sigil in the $#array form (7f315d2).

The internal structures of threading now make fewer API calls and fewer allocations, resulting in noticeably smaller object code. Additionally, many thread context checks have been deferred so that they're only done when required (although this is only possible for non-debugging builds).

xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and on some systems will cause struct xpvhv to become cache aligned. To avoid this memory saving causing a slowdown elsewhere, boolean use of HvFILL now calls HvTOTALKEYS instead (which is equivalent) - so while the fill data when actually required is now calculated on demand, the cases when this needs to be done should be few and far between (f4431c .. fcd245).

The order of structure elements in SV bodies has changed. Effectively, the NV slot has swapped location with STASH and MAGIC. As all access to SV members is via macros, this should be completely transparent. This change allows the space saving for PVHVs documented above, and may reduce the memory allocation needed for PVIVs on some architectures.

The foldEQ_utf8 API function for case-insensitive comparison of strings (which is used heavily by the regexp engine) was substantially refactored and optimised - and its documentation much improved as a free bonus gift (8b3587, e6226b).

glob() no longer crashes when %File::Glob:: is empty and CORE::GLOBAL::glob isn't present (4984aa).

perlbug now always permits the sender address to be changed before sending - if you were having trouble sending bug reports before now, this should fix it, we hope (e6eb90).

Overloading now works properly in conjunction with tied variables. What formerly happened was that most ops checked their arguments for overloading before checking for magic, so for example an overloaded object returned by a tied array access would usually be treated as not overloaded (RT #57012) (6f1401, ed3b9b, 6a5f8c .. 24328f).

OpenBSD > 3.7 has a new malloc implementation which is mmap based and as such can release memory back to the OS; however for perl using this malloc causes a substantial slowdown so we now default to using perl's malloc instead (RT #75742) (9b58b5).

Perl 5.13.2 represents thirty days of development since Perl 5.13.1 (and two days of waiting around while the release manager remembered where he left his brain) and contains 3685 lines of changes across 194 files from 30 authors and committers.

Your humble release manager would like to specifically call out Karl Williamson for making the tests a better place to be, and Shlomi Fish for a passel of tiny incremental docfixes of the sort that don't get made often enough.

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at http://rt.perl.org/perlbug/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.